I'm a little confused about what is the "correct behavior" of ATAPI DMA INTRQ.
1. The ATA-4 flowchart and ATA-6 state diagram seems to be inconsistent. In the ATA-4 flowchart, no wait for INTRQ is specified.
2. From the ATA-5 errata: http://www.t13.org/project/e01122r0.pdf
"...Page 265 through 270 of NCITS 340-2000 clause 9.8 was not properly converted from the flow charts in NCITS 317-1998 to the state diagrams. The state diagrams figures 33 and 34 and associated text is modified to indicate that the device interrupts only at command completion. "
Notice the "device interrupts only at command completion." statement. However, the diagrams in the errata are inconsistent with the above statement.
3. The ide-cd code does not wait for INTRQ before starting BM-DMA
/* Arm the interrupt handler. */ ide_set_handler(drive, handler, rq->timeout, cdrom_timer_expiry);
/* ATAPI commands get padded out to 12 bytes minimum */ cmd_len = COMMAND_SIZE(rq->cmd[0]); if (cmd_len < ATAPI_MIN_CDB_BYTES) cmd_len = ATAPI_MIN_CDB_BYTES;
/* Send the command to the device. */ HWIF(drive)->atapi_output_bytes(drive, rq->cmd, cmd_len);
/* Start the DMA if need be */ if (info->dma) hwif->dma_start(drive);
return ide_started;
This is a good point, and refreshes my memory on the subject from when the code was written (and updated by Bart).
I'll look into things further...
Jeff
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